The way I had my rooms set up, I didn't really have any mommies. It was more like three grandmas and a whole bunch of new mommies every cycle. I had two rooms; one for clones and veg, the other for flowering.
After harvesting the flowering room, I'd give it a good scrubbing, from top to bottom. Then, right before I'd transfer my veg plants to the flowering room, I'd take a bunch of clones off of several of the plants. Those clones would grow in the veg room until it was time to switch 'em over. Because I had so many plants to choose from I could be picky. I only took clones from the strongest, healthiest plants, which insured a hardy bunch of plants. And when they went into the flowering room, it was sterile and bug free. It was nice little cycle I had going.
For some reason, I never really had a problem with them in the veg side (I think they knew the good stuff was in the other room). But no matter how hard I tried, I never could keep those little bastards out of the flowering room. They're like the Michael Jordan of bugs. You can't stop 'em. You can only hope to contain them. I did pretty good though.